Process of gasifying combustible materials



9, 1958 R. RUMMEL ETAL 2,848,473

PROCESS OF GASIFYING COMBUSTIBLE MATERIALS Filed June ;L6, 1953 2 I0 24 25 26 7 INVENTORS RUDOLF HUTTNER, ROMAN RUMMEL.

16,. AT ORNEYS Patented Aug. 19, 1958 PROCESS OF GASIFYING COMBUSTIBLE MATERIALS Application June 16, 1953, Serial No. 362,051

Claims priority, application Germany June 19, 1952 7 Claims. (Cl. 260449) This invention relates to a new process of producing ric gases and more particularly it relates to new and useful improvements in the gasification of combustible materials.

It is known to produce gases by gasifying combustible materials, particularly coal, in their own liquid slag. According to a specific process the liquid slag is maintained in undulating and circulatory movement by the flow energy of the gasifying agent or agents and the combustible material flowing into the slag. The gasifying agents by reacting exothermically with the combustible material and the slag, on the one hand, and with the combustible material, and if desired also the endothermic gasifying reactant, on the other hand, are introduced into the slag which is maintained in a substantially cyclic current in such a manner that the fuel is destructively distilled and partially gasified in one part of the circuit while the slag is again heated to the temperature required for gasification in another part of the circuit. This process is described in copending application Ser. No. 92,832, filed by Roman Rummel and issued as U. S. Patent No. 2,647,045 on July 28, 1953.

In the further development of the above described inventive concept we have found that a particularly rich gas, i. e. a gas which is high in combustible constituents and low in inert components such as nitrogen, is obtained by enriching the gases produced in the gasifying space containing the endothermic reactants, with hydrocarbons. The new process may be carried out by introducing into the hot gases, which have a temperature of, for instance, about 1500 C., bituminous substances such as coal, lignite, peat and oil shale, preferably in particle or dust form.

The gases produced according to the invention are very valuable in commercial usage, for instance as long distance gas.

It is therefore an object of the invention to provide a new and improved method for the gasification of combustible materials and particularly those of the coal type.

This and further objects of the invention may be seen from the following description read in conjunction with the accompanying diagrammatic flowsheets which illustrate some embodiments of the invention wherein Fig. 1 illustrates one embodiment of the invention and Fig. 2 illustrates a second embodiment thereof.

Referring to Fig. 1, there are provided a heating space 1 and a gasifying space 2 of a gasifying apparatus substantially as described in said Patent No. 2,647,045, a destructive distillation space 3, a coke separator 4, a coal drier 5, a separator 6 for separating the dried coal whilst in suspension, a washer 7, a boiler S, and a feed-water preheater 9. The ducts 15 and 16 supply air and feed-water and the ducts 1'7 and 18 lead the flue gas and steam away to the outer atmosphere. The fuel, for instance lignite, predried to 15% water content, enters the apparatus through the duct and is carried by the gas stream issuing from the destructive distillation space 3the gas stream has a temperature of for instance 750 C.- through the coal drier 5. On this passage the Water content of the fuel is reduced to 2%.

A part of the dried coal is led through the duct 11 to the gasifying space 2 of the apparatus with the aid of steam introduced through the duct 12 or another conveying medium, and the rest of the dried coal is led through the duct 14 into the destructive distillation space 3. It is within the scope of the invention to admit additional steam elsewhere, for instance via the duct 13.

Besides the coke conveyed into the heating space 1 with the recycled slag, further quantities of coke, which are supplied for instance from the coke separator 4, may be admitted into the heating space 1 of the slag bath. A1- ternatively, a larger or smaller portion of the coke coming from the separator 4 may be conveyed into the gasifying space 3 of the apparatus.

The combustion gases generated in the heating space 1 are utilized for producing steam in the boiler 8 and the feed-water preheater 9. The gas issuing from the gasifying space 2 of the slag bath with a temperature of about 1500 C. flows into the destructive distillation space 3 and enters the coal drier 5 at a temperature of about 750 C. after passing through the coke separat0r 4. The gas escaping from the separator 6 is purified in the washer 7 and, after that, obtained with the calorific value H =3300 kcal. (through the duct 19). The flue gas can also be used to predry the crude lignite to 15% water content. 1

According to another embodiment of the invention liquid or gaseous substances containing hydrocarbons, such as tars and residues obtained in cracking and hydrogenation processes, are introduced into the gas issuing from the gasifying space of the slag bath. Within this procedure, it is possible to vary the calorific value of the resultant products by varying the quantities and temperatures of the components.

If the process is carried out for the purpose of producing a gas with a more or less substantial content of unsaturated hydrocarbons, the solid, liquid or gaseous fuels may be introduced under conditions providing an actual contact with the surface of the slag. As an alternative to this embodiment, the fuels may be admitted at a greater distance from the surface of the slag; but this distance cannot be too great, however, since the heat emitted by the slag must still be effective for the purpose.

A preferred embodiment in enriching the gases with unsaturated hydrocarbons is to maintain the heat effective for a limited period of time only. The content of unsaturated hydrocarbons in the gas can further be adjusted by controlling the temperature of the slag and the concentration of the fuels employed. Moreover, it is of importance to freeze, i. e. to fix by chilling, the equilibria reached, in particular with respect to the reactive unsaturated hydrocarbons; this may be accomplished by conventional methods.

Another preferred embodiment of the invention consists in conducting the hot gases that are produced in the gasifying space of the slag bath and consist substantialiy of CO and H over catalytically active substances which eifect conversion of the CO and H to hydrocarbons. Examples of such active substances are the known catalysts causing methane formation, especially those containing nickel.

A converter may be provided into which the gases are passed before conducting them over the catalysts effecting methane formation. This offers the advantage that the gas collected from some larger gasifying units can be converted to methane in a single space, and simultaneously provides a simple and convenient method of adjusting the calorific value of the gas. Furthermore, it

is not necessary to remove any sewage slurry. The water gas produced in the gasifying space of the apparatus contains no tar or resin forming substances or sulfur compounds, which are .difiicult to remove, and therefore desulfurization andthe choice of the catalyst involve 'no difiiculties; this renders the application of the process in this combination particularly useful.

It is further within the scope of the invention to produce a rest gas of high calorific value after removing liquid products by conducting the gas produced by the herein described process, which is of high quality, over catalysts commonly applied in the synthesis of hydrocarbons according to the Fischer Tropsch process.

Fig. 2 exemplifies the conversion of fuels to gases in the presence of catalysts inducing methane formation. There are further possible variations of the new process depending upon whether the same is carried into effect under atmospheric or superatmospheric pressure.

According to the process illustrated in Fig. 2, predried lignite having 15% water content is fed through the duct into the gasifying space 2 of the slag bath. After passing the waste-heat boiler 8a the water gas produced in the gasifying space at high temperatures flows via the washer 7, the gasorneter 21, the compressor 22 and the dust separator 24 into the space where conversion to methane takes place. After removing the carbon dioxide the gas is ready for industrial purposes, for instance in the gas grid.

The air admitted through the duct enters into the heating space 1 of the slag bath after being preheated in the heater 20. After passing through the waste-heat boiler 8b, the air preheater and the feed-water preheater 9, the flue gas produced in the heating space 1 is led away to atmosphere. Feed-water is supplied through the duct 16. The steam produced in the waste-heat boilers 8a and 8b is led away through the duct 17 to atmosphere. The duct 27 serves to lead away the slag.

The process of the invention permits the use of fuels of all kinds, for instance high-ash coal, non-baking and baking fuels. Furthermore, it shows the advantage that the fuels employed are converted to gas without leaving any substantial residue; this obviates the necessity of recovering and working up residual and waste products.

We claim: 1. A process for producing gases high in combustible constituents and low in inert compounds which comprises introducing fuels into molten slag together with an exothermic combustion supporting gas and an endothermic gasification reactant for said fuels to produce a combustible gas mixture therefrom, and introducing carbonaceous material into said combustible gas mixture at a position adjacent the surface of the slag to utilize the heat of the-slag to crack the carbonaceous materials resulting in the formation of low molecular gaseous hydrocarbons in admixture 'with said combustible gas mixture.

2. The process of claim 1 wherein said carbonaceous materials are selectedfrorn the group consisting of coal, lignite, oil shale, liquid carbonaceous fuels and gaseous carbonaceous fuels.

3. The process of claim 1 wherein said carbonaceous materials are introduced into the combustible gas mixture in spaced relationship to the surface of the slag in position to receive a substantial portion of the heat energy given up by the slag.

4. The process of claim 1 wherein the gaseous hydrocarbons are substantially unsaturated.

5. The process of claim 1 wherein the gaseous hydrocarbons are substantially unsaturated, the carbonaceous materials are introduced within a predetermined short time interval and wherein an equilibrium of the quantity of unsaturated hydrocarbons in the gas mixture is maintained.

6. The process of claim 5 wherein said equilibrium is obtained by chilling.

7. The process of claim 1 wherein the combustible gas mixture includes CO and H and is passed over catalytically active substances for inducing the hydrogenation of the CO by the H to form methane.

References Cited in the file of this patent UNITED STATES PATENTS 1,083,683 Hirt Jan. 6, 1914 1,559,622 Klotzer Nov. 3, 1925 2,047,499 Towne July 14, 1936 2,111,579 Winkler et al. Mar. 22, 1938 2,126,150 Stryker Aug. 9, 1938 2,449,729 Steinschlaeger Sept. 21, 1948 2,527,154 Scharmann Oct. 24, 1950 2,647,045 Rummel July 28, 1953 2,657,124 Gaucher Oct. 27, 1953 2,738,262 Benz et al Mar. 13, 1956 

1. A PROCESS FOR PRODUCING GASES HIGH IN COMBUSTIBLE CONSTITUENTS AND LOW IN INERT COMPOUNDS WHICH COMPRISES INTRODUCILNG FUELS INTO MOLTEN SLAG TOGETHER WITH AN EXOTHERMIC COMBUSTION SUPPORTING GAS AND AN EXOGASIFICATION REACTANT FOR SAID FUELS TO PRODUCE A COMBUSTIBLE GAS MIXTURE THEREFROM, AND INTRODUCING CARBONACEOUS MATERIAL INTO SAID COMBUSTIBLE GAS MIXTURE AT A POSITION ADJACENT THE SURFACE OF THE SLAG TO UTILIZE THE HEAT OF THE SLAG TO CRACK THE CARBONACEOUS MATERIALS RESULTING IN THE FORMATION OF LOW MOLECULAR GASEOUS HYDROCARBON IN ADMIXTURE WITH SAID COMBUSTIBLE GAS MIXTURE. 